Wet refuse burning grate



Nov. 23, 1937. J. SCHRENK WET REFUSE BURNING GRATE Filed May 25, 1935 2Sheets-Sheet l INVENTOR LOU/6 J SCH/Pf/VK BY V IIIIIII I ATTORNEY Nov.23, 1937. L. J. SCHRENK 2,099,827

WET REFUSE BURNING GRATE Filed May 25, 1935 2 Sheets-Sheet 2 Q o 4L 32 iiium ATTORNEY Patented Nov. 23, 1937 UNITED STATES PATENT OFFICE 1Claim.

This invention relates to a grate, or hearth, for burning wet fuels and,particularly, to such a grate used in conjunction with auxiliary firingas with pulverized fuel.

5 In burning wet fuels, such as garbage, sewage screenings and the like,or mixtures of wet and dry fuels within the furnace of a steam boiler,as is disclosed in my co-pending application, Serial No. 719,637, filedApril 9, 1934, I have found that burning is materially improved if thewet fuel is agitated. This application is a continuation in part of saidapplication.

One object of the present invention is to provide in a furnace forburning wet fuels, where combustion is augmented by supplementary fuel,the combination of a fluid-cooled grate and means for agitating the wetfuel, the grate serving to cool and protect the agitating means.

Other objects and advantages of the invention 20 will become apparentupon consideration of the following detailed description and theappended claim when read in conjunction with the accompanying drawingsin which:

Figure 1 is a cross-sectional elevation of a boiler and furnaceinvolving the invention.

Figure 2 is a plan View of a portion of the grate;

Figure 3 is an enlarged side elevation partly in section of a portion ofthe grate and shows the 30 construction and operating means for the fuelagitators in one form thereof;

Figure 4 is a section on line 44 in Figure 3.

Figure 5 is a section on line 55 in Figure As shown in Figure 1, the wetrefuse is burned on a fluid-cooled grate If] which is at the bottom of afurnace II. Another or supplementary fuel is burned and directed intothe furnace so that its flame may impinge or pass over the surface ofthe wet fuel to be burned. Such other 40 fuel may be in the form of apulverized fuel stream which as shown is directed downwardly by burnersl2, the flames l3 descending toward the grate I0, and thence bendingupwardly in the shape of a U and leaving the furnace at the upper end.The furnace in this case is surmounted by a steam boiler M of a usualtype, for absorbing the heat from the gases leaving the furnace.

The grate or hearth l comprises a plurality of spaced tubes extendinglongitudinally of the furnace, the tubes being connected into headers l6and I1, and thence through downcomers l8 and risers 20 to the steam andwater drum 2| of boiler I4 for circulation of boiler water therethrough.At the end of the grate where the wet fuel enters, the intertube spacesof the grate are covered by blocks or tiles 22, preferably of cast iron,arranged to have air spaces 23, Figure 4. Further down the grate Iprovide several transverse rows of oscillatable agitators 5 24, andbelow these the intertube spaces are again covered by similar tiles 22.Compartments 25 may be formed by partitions 26 to divide the air spacebeneath the grate into zones delivering air at different volumes andpressures through the related sections of the grate.

The wet fuel, in this case garbage or a mixture of garbage and rubbish,enters through the hoppers 21 of a feeding mechanism which, in thiscase, consists of a multiplicity of reciprocable feeding rams 28, whichare arranged in horizontal alignment across the grate. The rate of feedmay be varied by the number of strokes the rams make in a given time.From the hoppers 27, the wet fuel falls in front of the feeding rams 28,on their rearward stroke, and is pushed into the furnace H onto thegrate H] on the forward stroke of the rams. On the grate the fuel mayassume the general shape shown in Figure 1. The flames E3 of thesupplementary fuel stream 25 sweep over the wet fuel bed in a directionopposite to that of the wet fuel travel down the grate and the hightemperature of these flames supplies the heat for drying and ignitingthe wet fuels.

I have found that combustion of the wet fuel may be materially improvedby providing the agitators 24 which are adapted to be oscillated throughan angle of to turn the fuel bed over so that its constituents may bethoroughly and repeatedly exposed to the drying and consuming action ofthe flames in the furnace. The agitators are, preferably, made of ironor steel in the forms of sectors of a circle and arranged in rows, inthis instance three, transversely of the grate.

As shown in Figure 3, the agitators are in the form of quadrantsoscillatable about pivot pins 30 carried by cast iron or steel plates 3|supported on and between pairs of grate tubes l5, Figure 5. The plates3| are formed with slots 32 through which the agitators are oscillatableand which are normally occupied by the apertured radially extending topsurfaces 33 of the agitators that support the wet fuel as it passesthereover down the grate. The apertured top surface 33 of each agitator24 comprises a series of inclined overlapping slats or plates 34spacedly mounted between sectional side plates 35 of the agitator. Thetop plates 34 are disposed at a downward angle to the upper radial edge33 of along the grate. When an agitator is swung into the furnace, theside plates 35, depending below the top plates 34 and an arcuate plate31 mounted between the plates 35- maintain the slot 32- in plate 3|closed. This results in preventing air being blown into, the furnacethrough the sides and ends of the agitators and also precludes fuelfalling through the latter from adjacent portions of grate i0.

The number of agitators 24 in each transverse row depends on the Widthof thefurnace. All of the agitators in .a transverse row may be operatedby a pressure cylinder 40, or the agitators of a row may be divided intogroups operable by cylinders individual to the respective groups.

Each agitator is connected by a linkage 4| to a' 'rock shaft 42 operablein turn by the piston associated with the cylinder) through a linkage g43. 'The valves 44 for controlling the operation of the severaltransverse rows of agitators, or the groups of each row, may beconveniently located, as at the side of the furnace, for manual control.If desiredthe valve control 'members '45 may be mechanically orelectrically connected with the operating mechanism of rams 28 forautomaticactuation in any desired relation. to the latter. J 7

As the Wet fuel is fed into the furnace it is V exposed to the dryingand consuming action of the flames in the furnace as it is advancedalong the grate on the introduction of successive charges by the'rams28. The air jets directed through passages 36 in the agitators not onlysupply air for combustion but also assist in drying the wet fuel andmoving it along the grate. when the agitators 24 are oscillated they actto push the wet fuel downwardly through thegrate'and 'm entary fuelalone would be used. In either case,

the wet fuel grate and the agitators would be subject to-considerableheat, since the protection of the wet fuel is then minimized or may evenbe .removed. Under such circumstances the fluidcooled tubes of the grateabsorb sufficient heat, mostly by'radiation from the agitators, toprotect them from burning or warping.

Although an illustrative embodiment of my invention has been shown anddescribed in detail herein, there are many changes and variationsthatmay be made without departing from the invention and which I,therefore, desire and intend to include within thescope of the followingclaim. What I claim is: V

In a refuse burning boiler and furnace installa' tion having'a boiler,acombustionchamber, an inclined perforate hearth in' said chamber, meansfor feeding refuse to the hearth and means for supplying air underpressure through the hearth and the bed of refuse thereon; a pluralityof pivoted agitators. interposed in the hearth and operable to advancethe fuel therealong, 'sai d agitators each having fuel contactingsurfaces in cluding a plurality of plates disposed horizontally andarranged in overlappedrelation with their adjacent ends spa'ced'to forma 'p'luralit'yof "air passages inclined relatively to the surface ofsaid hearth for directing air flowing through said passages underpressure in such'manner as to assist in moving the fuel along thehearth. r r LOUIS J. SCHRENK.

